Subject: RE: [Sip] RFC 3261 supported header in 1xx responses

From: "Arunachalam Venkatraman \(arunvenk\)" <[email-masked]>
Date: Fri, 18 Nov 2005 17:04:07 -0800

Can a proxy add Supported? Is this disallowed?
If proxy may do so, the Supported cannot be interpreted as UAS
capabilities, even if the 1xx is reliable (consider INVITE with
Require:100rel).

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Jonathan Rosenberg (jdrosen)
Sent: Friday, November 18, 2005 5:39 PM
To: Brett Tate
Cc: sip-ietf
Subject: Re: [Sip] RFC 3261 supported header in 1xx responses

It makes sense to include them in a dialog forming response. A normal
1xx is not dialog forming. My suspicion (though I didn't check if this
was true) is that it went away when 100rel moved out of 3261. It can't
hurt to send them, of course, but it would be ignored unless its
reliable.

-Jonathan R.

Brett Tate wrote:

> Within early versions of draft-ietf-sip-rfc2543bis, the Supported 
> header could be expected within 1xx responses.  However within
> draft-ietf-sip-rfc2543bis-06 it was removed and remains so within RFC
3261.
> Is there a reason why it is undesirable to indicate supported 
> extensions within a 1xx?  Or was it just an oversight when changing 
> the "Summary of header fields" table to indicate 2xx instead of all
responses?
> 
> 
> 
> 
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-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Director, Service Provider VoIP Architecture   Parsippany, NJ 07054-2711
Cisco Systems
[email-masked]                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
http://www.cisco.com

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol Use
[email-masked] for questions on current sip Use
[email-masked] for new developments on the application of sip

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip

---

From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 21 Nov 2005 10:00:03 -0500

If a proxy genreates the 1xx itself, it is effectively acting as a UAS, 
in which case insertion of Supported is fine. This won't confuse a UAC 
since any 1xx generated by the proxy itself will have different tags 
from a 2xx or other responses generated by the actual UA, and thus 
represent a different (early) dialog.

A proxy cannot insert or modify a Supported header in a response that 
passes by it (i.e., one for which it is proxying).

-Jonathan R.